Piping and pipeline are considered to be 60-70% of the oil and gas industry equipment. One of the most crucial factors to complete high quality projects within planned schedules is to focus on the quality of welding activities. Furthermore, the non-skilled welder is considered as a main parameter to produce welds with imperfections beyond the acceptable limits. Welders should have the required welding skills to perform the welding activities and produce sound welds, resulting in low weld rejection. On the other hand, poor welder’s performance produces low quality welds which affect the integrity of the welds and contribute to project delay and increase costs. This paper addresses methods to qualify welders and monitor their performance throughout the project lifecycle. The paper will study ISO 9606 approval testing of welders, American Welding Society (AWS) and American Society of Mechanical Engineers (ASME) Sec IX minimum requirements to qualify and certify welders. It will also illustrate the main variables that may contribute to high welding rejection rate, that are directly associated with the welders’ qualification and performance. Moreover, it will study the method of qualifying welders for different levels to properly assign welders based on load and criticality to avoid high welding rejection rate. The study shows that welders’ skill is the main parameter to produce high quality welds. Focusing on the causes of common welding defects, then educate and train the welders on the main factors causing these welding defects, will leave an influence to prevent defect recurrence